(a) Field of The Invention
This invention relates to drive belts having a belt body made of ethylene-α-olefin elastomer composition.
(b) Description of The Related Art
Various sheet handling machines and equipment, including printers and automatic vending machines, use a light-duty toothed belt for conveying sheets, such as paper sheets, bank notes or cards. Such a light-duty toothed belt is required to have high flexibility and small bending resistance for the purpose of compaction of a drive source due to space saving and, naturally, also required to have excellent conveying capability.
Published Japanese Patent Application No. H07-77244 discloses a conveying toothed belt that includes a plurality of teeth disposed at specified intervals in the longitudinal direction of the belt and a backing rubber having a longitudinal cord embedded therein, wherein a longitudinally continuous, electrical conducting layer is disposed in a tooth side rubber of the belt and at least part of the electrical conducting layer is exposed at a contact surface with a pulley or a flange for the pulley. Further, the document describes that with the above configuration, the belt body can be prevented from static electrification, whereby the carrying surface of the belt can be protected against adhesion of pieces coming from paper sheets carried thereon, foreign particles and dusts and prevented from reduction in coefficient of friction.
Published Japanese Patent Application No. H09-144816 discloses a toothed belt including a plurality of teeth disposed along the lengthwise direction, a backing part having a cord embedded therein and a facing fabric covering the surfaces of the teeth, wherein a rubber layer constituted by the backing part or the backing part and the teeth is doped at least with 5 to 80 parts by weight of powdered inorganic porous material as a porous filler with respect to 100 parts by weight of the rubber, the porous filler is exposed at the surface of the backing part by grinding and the rubber layer constituted by the backing part and the teeth is made of a rubber composition containing chloroprene rubber with crystallization resistance. Further, the document describes that with the above configuration, the belt can be used without trouble even under severe environmental temperature conditions, can maintain a constant coefficient of friction and flexibility even if oil or water adheres to the belt back face, can be prevented from contaminating conveyed objects, such as cards, bank notes and tickets, and can be reduced in rate of rotational variation and thereby increased in feeding accuracy.
Published Japanese Patent Application No. H09-295710 discloses a conveying toothed belt including a belt body having a cord embedded therein, a plurality of teeth projecting from the inner face of the belt body at lengthwise spaced intervals and a tooth fabric covering the surfaces of the teeth, the belt body and the teeth constituting a rubber layer, wherein the rubber layer constituted by the belt body and the teeth is made of a rubber composition containing chloroprene rubber with crystallization resistance, the belt can be prevented from increase in hardness due to crystallization of the rubber layer and decrease in coefficient of friction at low temperatures because the chloroprene rubber with crystallization resistance is less likely to crystallize even if it is allowed to stand for a long time under low-temperature environments. Further, the document describes that with the above configuration, the belt can be used without trouble even under severe environmental temperature conditions.
Published Japanese Patent Application No. H11-325190 discloses a toothed belt for conveying sheets including a rubber belt body, a large number of rubber teeth disposed on the surface of the rubber belt body at a specified pitch in the lengthwise direction of the belt to extend in the widthwise direction of the belt and a cord of substantially circular section embedded in the rubber belt body to extend in the lengthwise direction of the belt while being turned at a specified pitch in the widthwise direction of the belt, wherein the cord pitch is set twice to three times larger than the cord diameter, the tooth pitch is set not larger than 3 mm and the cord diameter is set not larger than 0.5 mm. Further, the document describes that with the above configuration, the belt bending stiffness can be decreased without changing the rubber material for the rubber belt body.
Published Japanese Patent Application No. H11-106080 discloses a conveying flat belt comprising a conveying rubber layer and a rubber-made tension retaining layer, wherein a high-modulus compound rubber exhibiting at least 1.0 to 20.0 MPa at 10% modulus is used as the rubber-made tension retaining layer, the conveying rubber layer preferably has a layered structure of rubber compounds with a coefficient of friction of 0.7 to 2.0 and the rubber-made tension retaining layer contains or uses, as means for enhancing the modulus, at lease one of carbon, reinforcing short fibers and rubber obtained by compounding a metallic salt of unsaturated carboxylic acid with an organic peroxide and crosslinking them. Further, the document describes that with the above configuration, the belt can be used at a stable tension with the center distance fixed, the positioning accuracy can be increased, disengage of the belt from the pulleys and offset and crinkles of conveyed objects can be prevented and the conveying accuracy is excellent.